Measurement of adhesion and bonding strength studies in 3D interconnect structures using atomic force microscopy

The wafer bonding process has become a flexible approach to material and device integration. The bonding strength in 3-dimensional processes is a crucial factor in various interface bonding processes such as silicon to silicon, silicon to metal, and oxide to adhesive intermediates. A method for measurement of bonding strength is proposed utilizing an ‘atomic force microscopy (AFM) applied carbon nanotube (CNT) probe tip’ which requires relatively simple preparation of sample and is able to measure bond strength regardless of film type. The bonding strength of the SiO 2 -Si surfaces cleaned with SPFM was 0.089 J/m 2 , while the bonding strength of surfaces cleaned with RCA 1 (NH 4 OH:H 2 O:H 2 O 2 ) was 0.044 J/m 2 . This work verified the possibility that the new method is capable of accurately measuring bonding strength. It was also confirmed that more effective bonding is possible after cleaning with SPFM.